خيارات البحث
النتائج 1421 - 1430 من 4,021
Distribution and depth profiles of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in sediment collected from offshore waters of Central Vietnam
2016
Tri, Tran Manh | Anh, Hoang Quoc | Tham, Trinh Thi | Van Quy, Tran | Long, Nguyen Quang | Nhung, Dao Thi | Nakamura, Masafumi | Nishida, Masayo | Maeda, Yasuaki | Van Boi, Luu | Minh, Tu Binh
Concentrations of PCBs and OCPs were measured in 35 surface sediment samples collected from offshore waters of Central Vietnam. The mean concentrations of PCBs, HCHs, and DDTs in surface sediments were 86.5, 37.0, and 44.5pgg−1, respectively. Additionally, nine PCDDs, eleven PCDFs, and twelve dl-PCBs were also examined in 19 sediment core samples collected from five locations. Concentration of PCDDs, PCDFs, and dl-PCBs ranged from 200 to 460, 0.39 to 2.9, and 1.6 to 22pgg−1, respectively. OCDD was detected at the highest concentration, ranged from 100 to 300pgg−1. Generally, the concentrations of PCDD/Fs at shallower depths were higher, meanwhile the depth profiles of dl-PCBs in sediment cores were different than the depth profiles of PCDD/Fs. The results suggest that the pollution of PCBs might be from many different sources leading to the variation between depths.
اظهر المزيد [+] اقل [-]Coral Sr/Ca-based sea surface temperature and air temperature variability from the inshore and offshore corals in the Seribu Islands, Indonesia
2016
Cahyarini, Sri Yudawati | Zinke, Jens | Troelstra, Simon | Suharsono, | Aldrian, Edvin | Hoeksema, B.W.
The ability of massive Porites corals to faithfully record temperature is assessed. Porites corals from Kepulauan Seribu were sampled from one inshore and one offshore site and analyzed for their Sr/Ca variation. The results show that Sr/Ca of the offshore coral tracked SST, while Sr/Ca variation of the inshore coral tracked ambient air temperature. In particular, the inshore SST variation is related to air temperature anomalies of the urban center of Jakarta. The latter we relate to air—sea interactions modifying inshore SST associated with the land-sea breeze mechanism and/or monsoonal circulation. The correlation pattern of monthly coral Sr/Ca with the Niño3.4 index and SEIO-SST reveals that corals in the Seribu islands region respond differently to remote forcing. An opposite response is observed for inshore and offshore corals in response to El Niño onset, yet similar to El Niño mature phase (December to February). SEIO SSTs co-vary strongly with SST and air temperature variability across the Seribu island reef complex. The results of this study clearly indicate that locations of coral proxy record in Indonesia need to be chosen carefully in order to identify the seasonal climate response to local and remote climate and anthropogenic forcing.
اظهر المزيد [+] اقل [-]Bioaccumulation and retention kinetics of cesium in the Milkfish Chanos chanos from Jakarta Bay
2016
Prihatiningsih, Wahyu Retno | Suseno, Heny | Zamani, Neviaty P. | Soedharma, Dedy
Laboratory radiotracer experiments were conducted to study the uptake, assimilation, and retention of cesium (137Cs) in milkfish (Chanos chanos) from Jakarta Bay. In this study, we have examined the bioaccumulation and distribution of 137Cs in C. chanos obtained from 137Cs-labeled seawater and 137Cs-labeled Artemia sp. feeding. The uptake of 137Cs via seawater displayed a one-compartment model suggesting that the concentration factors of 137Cs within the milkfish (weight 2.46–9.86g) at a steady-state period were between 10.66 and 3.98mLg−1 after 10days of exposure. The depuration rate was observed to be low, with only 22.80–49.14% of 137Cs absorbed by C. chanos, which was absent 6days after exposure. By contrast, depuration occurred quickly for radiolabeled food uptake, reaching 20% of retention within 10days after exposure. Muscles and viscera of the milkfish exhibited the highest degree of end uptake and end depuration of 137Cs from seawater and feeding.
اظهر المزيد [+] اقل [-]Trace Elements in Soils around Coal Mines: Current Scenario, Impact and Available Techniques for Management
2016
Sahoo, Prafulla Kumar | Equeenuddin, Sk. Md | Powell, M. A.
The present paper reviewed the average concentrations of trace elements in soils near coal mine areas from various cities/countries to provide a current global summary of this issue. The contamination of soils was assessed by using global reference materials and various contamination indices. The results show that the average concentrations of trace elements varied widely: As (0.5–38.3 mg/kg), Mn (86–3,700 mg/kg), Zn (1.5–296 mg/kg), Cu (0.5–110 mg/kg), Cr (17.5–954 mg/kg), Ni (4.3–390 mg/kg), Pb (0.5–433 mg/kg), Cd (0.02–4.48 mg/kg), and Hg (0.02–0.69 mg/kg). Most of these values are higher than the average world background soils and upper continental crust (UCC). The geo-accumulation (I gₑₒ) and contamination factor (CF) indices show that the contamination levels of Ni and Pb are higher than other elements. The potential ecological risk index (E ᵢ) suggests a high risk from Cd, especially in the Tabagi River watershed in Brazil and Ledo coal mines in India, and Hg, especially in Oltu (Turkey). The degree of contamination index (C d) reveals that the soils from Barapukuria (Bangladesh), Ledo (India), Ptolemais-Amynteon (Greece), and the Tibagi River (Brazil) have a higher degree of contamination than other sites. To control soil contamination, effective monitoring and legislative measures must be taken immediately. For the long term, various physical, chemical, and biological methods should be implemented. Although the selection of suitable methods is site-specific based on the extent and nature of contamination, in general, phytoremediation seems to be more beneficial and cost-effective than physical/chemical techniques.
اظهر المزيد [+] اقل [-]Manganese Removal from Drinking Water Sources
2016
Tobiason, John E. | Bazilio, Arianne | Goodwill, Joseph | Mai, Xuyen | Nguyen, Chuyen
Manganese (Mn) in drinking water can cause aesthetic and operational problems. Mn removal is necessary and often has major implications for treatment train design. This review provides an introduction to Mn occurrence and summarizes historic and recent research on removal mechanisms practiced in drinking water treatment. Manganese is removed by physical, chemical, and biological processes or by a combination of these methods. Although physical and chemical removal processes have been studied for decades, knowledge gaps still exist. The discovery of undesirable by-products when certain oxidants are used in treatment has impacted physical–chemical Mn removal methods. Understanding of the microorganisms present in systems that practice biological Mn removal has increased in the last decade as molecular methods have become more sophisticated, resulting in increasing use of biofiltration for Mn removal. The choice of Mn removal method is very much impacted by overall water chemistry and co-contaminants and must be integrated into the overall water treatment facility design and operation.
اظهر المزيد [+] اقل [-]Analysis of size-segregated winter season aerosol data from New Delhi, India
2016
Pant, Pallavi | Baker, Stephen J. | Goel, Rahul | Guttikunda, Sarath | Goel, Anubha | Shukla, Anuradha | Harrison, Roy M.
Size distributions of particulate matter and twelve constituent elements were measured at a high traffic site in New Delhi, India during winter 2013. While PM was found to be trimodal, individual elements showed varying size distribution patterns. Three key types of size distributions were observed including unimodal with peaks either in the coarse (Al, Si) or fine (Pb) modes, bimodal with peaks in the fine range (S) and multimodal with peaks in accumulation and coarse (Cu, Sb) modes. Elements such as Al, Si and Fe were found to be in predominantly in the coarse range while Cu, Zn, Pb and Sb were found to be in the fine size range. Two modes dominate the size distribution. One is coarse (ca. 3 μm) and contains mainly crustal elements and hence arises from sources such as soil, road dust, construction dust and possible coal fly ash. The other, more intense mode is fine (ca. 0.6 μm) and appears to comprise sulphate and anthropogenic trace metals which have entered the droplet mode through hygroscopic particle growth in the very high humidity conditions of the Delhi winter. A third, less intensive mode ca. at 0.2 μm probably arises from relatively fresh anthropogenic emissions which have not grown into the droplet mode.
اظهر المزيد [+] اقل [-]Microplastiques dans différents compartiments du cycle urbain de l’eau
2016
Dris, Rachid | Gasperi, Johnny | Rocher, Vincent | Tassin, Bruno | Laboratoire Eau Environnement et Systèmes Urbains (LEESU) ; AgroParisTech-École nationale des ponts et chaussées (ENPC)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12) | SIAAP - Direction du Développement et de la Prospective ; Syndicat interdépartemental pour l'assainissement de l'agglomération parisienne (SIAAP)
International audience
اظهر المزيد [+] اقل [-]Temporal and spatial distribution of semicarbazide in western Laizhou Bay
2016
Tian, Xiuhui | Xu, Yingjiang | Song, Xiukai | Gong, Xianghong | Liu, Yihao | Zhou, Quanli | Wang, Zhongquan | Xia, Chuanhai
Semicarbazide (SEM), an industrial raw material and the marker residue of nitrofurazone as a veterinary drug, has become a new type of marine pollutant. A standard method (ultra-performance liquid chromatography–tandem mass spectrometry, UPLC–MS/MS) was used to analyze SEM in seawater, sediment, and shellfish. A series of sections and stations were set up in radical distribution in western Laizhou Bay, with six voyages and 150 monitoring samples. The concentrations of SEM in seawater and shellfish were 10−11 and 10−10kg/L, respectively, and no SEM was detected in the sediment. Distribution characteristics at each state, temporal and spatial trends, multivariate analyses, and the causes were analyzed to assess the pollution level, which aimed to offer a database for drafting the national baseline values of SEM in seawater and sediment in future. The data obtained could be used for integrated watershed management of marine environment and economic activities for constructing a blue economic zone of Shandong Peninsula in China.
اظهر المزيد [+] اقل [-]The monetary valuation of acute respiratory illness from air pollution in Turkey
2016
Ara, Shihomi | Tekeşin, Cem
A contingent valuation study is conducted in three locations in Turkey using a total of 1362 observations to elicit willingness to pay (WTP) to avoid the acute respiratory illness (three days of severe coughing and throat pain). This is the first research of this kind in Turkey, and also one of a few studies conducted in developing countries. Median WTPs are estimated as 65, 51, and 83 PPP-adjusted 2012 USD for Afsin-Elbistan, Kutahya-Tavsanli and Ankara, respectively. Income elasticities of WTP are derived as 0.8 for Afsin-Elbistan and tested statistically indifferent from 1.0 for Kutahya-Tavsanli, and Ankara, and are found to be greater than the cases in existing studies conducted both in developed and developing countries. We also find that 60 to 90 percent of WTP are devoted for avoiding pain and discomfort/restricted activity days, and much less weights are given for avoiding possible financial losses. As for the determinants of WTP, university graduates, those who have experienced coughing within one month, have spent out-of-pocket medical expenses and actually lost some part of their income due the last experienced minor symptoms are willing to pay more to avoid the future acute respiratory illness while women and the household using coal as the main source of home-heating are willing to pay less in one or more study areas. New air quality standard for PM10 (transition from 150 μg/m3 to 40 μg/m3 by 2019) causes the reductions in minor respiratory symptoms by 11, 8, and 4.4 per person, and the resulting welfare gains are calculated as 157 million, 123 million, and 1464 million PPP-adjusted 2012 USD for Afsin-Elbistan, Kutahya-Tavsanli and Ankara, respectively.
اظهر المزيد [+] اقل [-]The possible role of bacterial signal molecules N-acyl homoserine lactones in the formation of diatom-biofilm (Cylindrotheca sp.)
2016
Yang, Cuiyun | Fang, Shengtao | Chen, Dehui | Wang, Jianhua | Liu, Fanghua | Xia, Chuanhai
Bacterial quorum sensing signal molecules N-acyl homoserine lactones (AHLs) (C10-HSL, 3-OXO-C10-HSL and 3-OH-C10-HSL) as possible chemical cues were employed to investigate the role in the formation of fouling diatom-biofilm (Cylindrotheca sp.). Results showed that AHLs promoted Chlorophyll a (Chl.a) and extracellular polymeric substance (EPS) contents in the diatom-biofilm. In the presence of AHLs-inhibitor 3, 4-Dibromo-2(5)H-furanone, which was used to avoid the possible interference of AHLs from bacteria, AHLs also increased the Chl.a and EPS contents. Scanning electron microscope and confocal laser scanning microscope analysis further demonstrated that AHLs promoted the formation of the diatom-biofilm. Non-invasive micro-test technique showed that AHLs promoted Ca2+ efflux in Cylindrotheca sp., which implied that Ca2+ might be correlated with AHLs-induced positive effect on the formation of diatom-biofilm. This study provides direct evidences that AHLs play an important role in developing the diatom-biofilm and AHLs-inhibitors might be promising active agents in marine antifouling.
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